I am inclined to agree with nchrome. A model that far out of balance IMHO has a basic design flaw. Best you can do is take as much weight out of the tail as possible, cram battery & servos forward, maybe substitute a heavier engine, then explore moving the engine forward a half inch or whatever it takes. You should be able to get someone to help you with the math if necessary to calculate how far forward to go. Basically a question of calculating moments. With a toy balsa glider you just move the wing back. There are no fixes for such a drastic problem that don't either take a lot of work or look a little strange. Sometimes the best fix is start a new model. The fun part of this hobby is flying, not rehabilitating hopeless cases. I used to say in my fishing days, I enjoy a challenge, but before I go home I want a good fish!